package main

import (
	"context"
	"crypto/tls"
	"encoding/json"
	"fmt"
	"net/http"
	"regexp"
	"strings"

	"github.com/go-irc/irc"
	"github.com/pkg/errors"
	log "github.com/sirupsen/logrus"
)

var regexpHostNotification = regexp.MustCompile(`^(?P<actor>\w+) is now(?: auto)? hosting you(?: for (?P<amount>[0-9]+) viewers)?.$`)

type ircHandler struct {
	conn *tls.Conn
	c    *irc.Client
	user string
}

func newIRCHandler() (*ircHandler, error) {
	h := new(ircHandler)

	username, err := h.fetchTwitchUsername()
	if err != nil {
		return nil, errors.Wrap(err, "fetching username")
	}

	conn, err := tls.Dial("tcp", "irc.chat.twitch.tv:6697", nil)
	if err != nil {
		return nil, errors.Wrap(err, "connect to IRC server")
	}

	h.c = irc.NewClient(conn, irc.ClientConfig{
		Nick:    username,
		Pass:    strings.Join([]string{"oauth", cfg.TwitchToken}, ":"),
		User:    username,
		Name:    username,
		Handler: h,
	})
	h.conn = conn
	h.user = username

	return h, nil
}

func (i ircHandler) Close() error { return i.conn.Close() }

func (i ircHandler) Handle(c *irc.Client, m *irc.Message) {
	switch m.Command {
	case "001":
		// 001 is a welcome event, so we join channels there
		c.WriteMessage(&irc.Message{
			Command: "CAP",
			Params: []string{
				"REQ",
				strings.Join([]string{
					"twitch.tv/commands",
					"twitch.tv/membership",
					"twitch.tv/tags",
				}, " "),
			},
		})
		c.Write(fmt.Sprintf("JOIN #%s", i.user))

	case "NOTICE":
		// NOTICE (Twitch Commands)
		// General notices from the server.
		i.handleTwitchNotice(m)

	case "PRIVMSG":
		i.handleTwitchPrivmsg(m)

	case "RECONNECT":
		// RECONNECT (Twitch Commands)
		// In this case, reconnect and rejoin channels that were on the connection, as you would normally.
		i.Close()

	case "USERNOTICE":
		// USERNOTICE (Twitch Commands)
		// Announces Twitch-specific events to the channel (for example, a user’s subscription notification).
		i.handleTwitchUsernotice(m)

	default:
		log.WithFields(log.Fields{
			"command":  m.Command,
			"tags":     m.Tags,
			"trailing": m.Trailing(),
		}).Trace("Unhandled message")
		// Unhandled message type, not yet needed
	}
}

func (i ircHandler) Run() error { return errors.Wrap(i.c.Run(), "running IRC client") }

func (ircHandler) fetchTwitchUsername() (string, error) {
	ctx, cancel := context.WithTimeout(context.Background(), twitchRequestTimeout)
	defer cancel()

	req, err := http.NewRequestWithContext(ctx, http.MethodGet, fmt.Sprintf("https://api.twitch.tv/helix/users?id=%s", cfg.TwitchID), nil)
	if err != nil {
		return "", errors.Wrap(err, "assemble user request")
	}
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Client-Id", cfg.TwitchClient)
	req.Header.Set("Authorization", "Bearer "+cfg.TwitchToken)

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return "", errors.Wrap(err, "requesting user info")
	}
	defer resp.Body.Close()

	var payload struct {
		Data []struct {
			ID    string `json:"id"`
			Login string `json:"login"`
		} `json:"data"`
	}

	if err = json.NewDecoder(resp.Body).Decode(&payload); err != nil {
		return "", errors.Wrap(err, "parse user info")
	}

	if l := len(payload.Data); l != 1 {
		return "", errors.Errorf("unexpected number of users returned: %d", l)
	}

	if payload.Data[0].ID != cfg.TwitchID {
		return "", errors.Errorf("unexpected user returned: %s", payload.Data[0].ID)
	}

	return payload.Data[0].Login, nil
}

func (ircHandler) handleTwitchNotice(m *irc.Message) {
	log.WithFields(log.Fields{
		"tags":     m.Tags,
		"trailing": m.Trailing,
	}).Debug("IRC NOTICE event")

	switch m.Tags["msg-id"] {
	case "":
		// Notices SHOULD have msg-id tags...
		log.WithField("msg", m).Warn("Received notice without msg-id")

	case "host_success", "host_success_viewers":
		log.WithField("trailing", m.Trailing()).Warn("Incoming host")

		// NOTE: Doesn't work? Need to figure out why, host had no notice
		// This used to work at some time... Maybe? Dunno. Didn't get that to work.

	}
}

func (ircHandler) handleTwitchPrivmsg(m *irc.Message) {
	log.WithFields(log.Fields{
		"name":     m.Name,
		"user":     m.User,
		"tags":     m.Tags,
		"trailing": m.Trailing(),
	}).Trace("Received privmsg")

	// Handle the jtv host message for hosts
	if m.User == "jtv" && regexpHostNotification.MatchString(m.Trailing()) {
		matches := regexpHostNotification.FindStringSubmatch(m.Trailing())
		if matches[2] == "" {
			matches[2] = "0"
		}

		subscriptions.SendAllSockets(msgTypeHost, map[string]interface{}{
			"from":        matches[1],
			"viewerCount": matches[2],
		})
	}
}

func (ircHandler) handleTwitchUsernotice(m *irc.Message) {
	log.WithFields(log.Fields{
		"tags":     m.Tags,
		"trailing": m.Trailing,
	}).Debug("IRC USERNOTICE event")

	switch m.Tags["msg-id"] {
	case "":
		// Notices SHOULD have msg-id tags...
		log.WithField("msg", m).Warn("Received usernotice without msg-id")

	case "raid":
		log.WithFields(log.Fields{
			"from":        m.Tags["login"],
			"viewercount": m.Tags["msg-param-viewerCount"],
		}).Info("Incoming raid")

		subscriptions.SendAllSockets(msgTypeRaid, map[string]interface{}{
			"from":        m.Tags["msg-param-displayName"],
			"viewerCount": m.Tags["msg-param-viewerCount"],
		})

	case "resub":
		// FIXME: Fill in later

	}
}